Testing for UV in the Midnight Sun

[nfoto]

Recently, Andrea and I spent a busy week in the Lofoten Archipelago in Northern Norway. This is 68 deg N so far north of the Polar Circle. Although technically speaking our stay was a few days shy of the start of true Midnight Sun season, it never got dark even in the night. Thus I could shoot my 400 mm lens hand-held at midnight. Usually a brave feat but not at 1/1000 sec :)

 

We stayed in a classic 'rorbu' (fishermen's cabin) on the Arctic Sea, at the little island Olnilsøy near Reine. Our daily view was an adjacent fishing village at the even smaller island Sakrisøy.

 

Here is the scene we saw, 24 hours a day (taken during an earlier stay, in 2011, but here up north the time passes slowly):

 

 

Boring. So we had to make it in UV, of course.

 

 

This was taken with the 24 mm f/2 Nikkor AIS.... wait, that's not a lens for UV, it can not be? Multi-coated, high-refraction glass, cemented elements, the list of objections goes on. However, neither the lens nor I cared much about that.

 

This is the beginning of a series of UV landscape test shots, using the following lenses: 24 mm f/2 Nikkor AIS, 35 mm f/3.5 Noflexar, 50 mm f/1.8 Nikkor AIS, 60 mm f/4 Coastal APO, 85 mm f/1.4 Nikkor AIS, UV-Nikkor 105 mm f/4.5. I shot with a modified Nikon D3200 that has internal Baader U2 (Venus) filter (courtesy Vivek Iyer).

 

The general conclusion is that any of these lenses can be used for UV landscapes. You will, as expected, get much shorter exposure times with the UV specialists (Coastal 60, UV-Nikkor 105), but for landscapes where tripod-mounted cameras are the norm, any lens - in principle - can be used. However, do stop down lenses to near their minimum aperture to get the better quality for UV work. Again, a recommendation against the usual 'rules', but tested and tried. I'll present an example of the improvement by stopping down later.

 

The major differences between the UV specialists and the 'non-UV' lenses are as follows,

• White-balancing in PhotoNinja against a UV-neutral target is possible for all lenses I tested. They all ended up at 2000 deg K (expected). However, the tint ranged from approx. -60 (UV-Nikkor, Coastal APO) to -85 to -95 (most others). The 35 mm Noflexar at -65 and 24 Nikkor at -75 were closest to the UV breed. This change in the tint setting indicates the non-UV lenses exhibit a cooler reddish cast with a tinge of magenta in it, compared to the warmer near orange-tinted output off camera for the UV specialists. However, by and large you can get similar landscape renditions with all of them after a proper run in PhotoNinja or other software capable of performing w/b in UV.
  

• Do not fear stopping down. I mean *far* down. The non-UV lenses did their best from f/11-f/16 (24/2, 50/1.8, 85/1.4). The UV specialists did their best around f/16 for this kind of work. Even f/32 with the UV-Nikkor or Coastal APO would be entirely acceptable. You can get a tad sharper images with the latter two at f/5.6-f/8, but the difference is very small compared to f/16 and the gain in increased depth of field worth the while.
  

• If you are on the outlook for 'weird' UV rendition, try a fast lens set wide or near wide open. You do need to use LiveView as the focus shift from what the finder shows can be very significant, though.
  

• The non-UV lenses in general requires at least 2, sometimes up to near 4 stops, more exposure. The 35 mm Noflexar, technically speaking not a UV specialist, comes closer at approx. 1.3 stop extra exposure.
  

• Do use the longest possible lens shade. The non-UV lenses can show traces of a 'UV hot-spot' if you don't take the necessary precautions. Needless to say, *any* ordinary filter has to be removed from the lens before you attempt to use it in UV ! This includes polarising filters as well.
  

[nfoto]

Here is what you can expect from the UV-Nikkor 105. at f/16. Do note that while setting up for the UV-Nikkor, I had to entertain our friendly landlady, a sweet old female aged 75 and as talkative and inquisitive as any up there in the high North. So given the distractions can't guarantee I did get it entirely right, but at least from f/11 onwards the images looked pretty sharp with the UV-Nikkor. I selected the f/16 exposure as a basis for the comparisons. From the original capture, you can identify the car by its maker's label (Volvo) on the other side of the harbour, a distance of about 250 m. The license plate reads 'YT 70438', last digital is difficult but think I got it right after comparing a few frames.

 

Exposure was 2.5 sec at f/16, 100 ISO. Not bad for an evening shot in UV .....

 

The crops shown below are 100% (pixelwise). I chose not to scale them, but forum software probably will interfere. Thus, view large.

 

 

I indicated in the opening post that a fast lens tentatively can be used in UV, but prepare yourself for a shocking result as all aberrations are there in the plenty, probably enhanced by UV too.

 

Here is the 100% view with the 85 mm f/1.4 Nikkor AIS at full bore. Plenty of optical nasties as can be seen, yet, there is a potential here to do alternate work in UV.

 

 

However, the 85 improves on stopping down, and at its smallest aperture f/16, we get this,

 

 

Oh dear. Every bit a match for the UV-Nikkor or possibly improving on it (consider the slight difference in scale between the two of them, however, and the likely sub-optimal UV-Nikkor result). OK, so it won't go very deep in UV, and you get 10-15 times longer exposures, but what a quality lens this reveals itself to be.

[colinbm]

Thanks very much Bjorn, these are beaut to see & thanks for the tech details :D

24 hours of daylight must be real strange :)

Cheers

Col

[nfoto]

"24 hours of daylight must be real strange"

 

Andrea found it pretty unsettling at first.

 

Basically you work or otherwise when you feel inclined to, eat when hungry, and go to sleep when you feel tired. Nobody bothers much about the actual time of the day.

[Alaun]

That's funny, I tested my little Olympus 45 1.8 for m43 with my GH3-UVIR and the Baader U last week and was surprised about its performance, though it goes only slightly into UV (blue comes good, yellow is just faintly visible)

 

Here a hand held shot at f1.8 ISO 1600 and 1/40 :

 

and a f1.8 ISO 1600 and 1/5:

 

and f2.0 ISO 800 and 1/6

 

Werner

 

(Some how I do not get the pictures here as I want, the Editor is showing only 3 tags ???)

[nfoto]

For non-documentary UV work such as moody captures or landscapes, I think the answer is many lenses can do a creditable job. However, once you need to penetrate more than skin deep into the UV band, you do need better performing lenses. otherwise say UV-specific marks won't come out properly or are washed out by IR contamination (as this issue rears its ugly head once you get a lens transmitting very little inside the UV range, but is fully open to any IR).

[Damon]

Wow how cool! Thanks so much for sharing. That is neat.

So could you use a telephoto lens as well? Do flowers just bloom all day long?

Are you putting the UV filter in front or behind the lens?

 

-D

[Andrea B.]

[Alaun: After you upload the files, place the cursor where you want a photo to appear and click the Add to Post button to the right of the file name.]

[Andrea B.]

Do flowers just bloom all day long?

Some do, some do not. Some are open in the am the close in the afternoon. And others are closed in the morning and open in the pm. Some bloom only at night.

 

Are you putting the UV filter in front or behind the lens?

Works well either way.

[nfoto]

In this particular case, I used a D3200 with the UV bandpass filter inside the camera. Makes life so much easier in some, not all, situations.

[msubees]

Nice shots. I tried my Panasonic 14-42 F3.5-5.6 G-VARIO ASPH MEGA O.I.S yesterday for a house and it also shows UV image...did not check for quality yet on a computer.